I get the freezing issues whenever there is a vehicle driving on my screen. Spawning it for myself, remote controlling a unit, or having an AI unit drive around while I watch all seems to have the same effect.
Tried both, still getting the same result, freezing when running the game without the launcher.
EDIT: It should be noted that though going through the launcher on the Steam Dev branch fixes the freezing issues, this "fix" does not work on stable.